| Current File : //usr/include/pg_config_manual.h |
/*------------------------------------------------------------------------
* PostgreSQL manual configuration settings
*
* This file contains various configuration symbols and limits. In
* all cases, changing them is only useful in very rare situations or
* for developers. If you edit any of these, be sure to do a *full*
* rebuild (and an initdb if noted).
*
* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/pg_config_manual.h
*------------------------------------------------------------------------
*/
/*
* This is the default value for wal_segment_size to be used when initdb is run
* without the --wal-segsize option. It must be a valid segment size.
*/
#define DEFAULT_XLOG_SEG_SIZE (16*1024*1024)
/*
* Maximum length for identifiers (e.g. table names, column names,
* function names). Names actually are limited to one less byte than this,
* because the length must include a trailing zero byte.
*
* Changing this requires an initdb.
*/
#define NAMEDATALEN 64
/*
* Maximum number of arguments to a function.
*
* The minimum value is 8 (GIN indexes use 8-argument support functions).
* The maximum possible value is around 600 (limited by index tuple size in
* pg_proc's index; BLCKSZ larger than 8K would allow more). Values larger
* than needed will waste memory and processing time, but do not directly
* cost disk space.
*
* Changing this does not require an initdb, but it does require a full
* backend recompile (including any user-defined C functions).
*/
#define FUNC_MAX_ARGS 100
/*
* Maximum number of columns in an index. There is little point in making
* this anything but a multiple of 32, because the main cost is associated
* with index tuple header size (see access/itup.h).
*
* Changing this requires an initdb.
*/
#define INDEX_MAX_KEYS 32
/*
* Maximum number of columns in a partition key
*/
#define PARTITION_MAX_KEYS 32
/*
* Decide whether built-in 8-byte types, including float8, int8, and
* timestamp, are passed by value. This is on by default if sizeof(Datum) >=
* 8 (that is, on 64-bit platforms). If sizeof(Datum) < 8 (32-bit platforms),
* this must be off. We keep this here as an option so that it is easy to
* test the pass-by-reference code paths on 64-bit platforms.
*
* Changing this requires an initdb.
*/
#if SIZEOF_VOID_P >= 8
#define USE_FLOAT8_BYVAL 1
#endif
/*
* When we don't have native spinlocks, we use semaphores to simulate them.
* Decreasing this value reduces consumption of OS resources; increasing it
* may improve performance, but supplying a real spinlock implementation is
* probably far better.
*/
#define NUM_SPINLOCK_SEMAPHORES 128
/*
* When we have neither spinlocks nor atomic operations support we're
* implementing atomic operations on top of spinlock on top of semaphores. To
* be safe against atomic operations while holding a spinlock separate
* semaphores have to be used.
*/
#define NUM_ATOMICS_SEMAPHORES 64
/*
* MAXPGPATH: standard size of a pathname buffer in PostgreSQL (hence,
* maximum usable pathname length is one less).
*
* We'd use a standard system header symbol for this, if there weren't
* so many to choose from: MAXPATHLEN, MAX_PATH, PATH_MAX are all
* defined by different "standards", and often have different values
* on the same platform! So we just punt and use a reasonably
* generous setting here.
*/
#define MAXPGPATH 1024
/*
* PG_SOMAXCONN: maximum accept-queue length limit passed to
* listen(2). You'd think we should use SOMAXCONN from
* <sys/socket.h>, but on many systems that symbol is much smaller
* than the kernel's actual limit. In any case, this symbol need be
* twiddled only if you have a kernel that refuses large limit values,
* rather than silently reducing the value to what it can handle
* (which is what most if not all Unixen do).
*/
#define PG_SOMAXCONN 10000
/*
* You can try changing this if you have a machine with bytes of
* another size, but no guarantee...
*/
#define BITS_PER_BYTE 8
/*
* Preferred alignment for disk I/O buffers. On some CPUs, copies between
* user space and kernel space are significantly faster if the user buffer
* is aligned on a larger-than-MAXALIGN boundary. Ideally this should be
* a platform-dependent value, but for now we just hard-wire it.
*/
#define ALIGNOF_BUFFER 32
/*
* If EXEC_BACKEND is defined, the postmaster uses an alternative method for
* starting subprocesses: Instead of simply using fork(), as is standard on
* Unix platforms, it uses fork()+exec() or something equivalent on Windows,
* as well as lots of extra code to bring the required global state to those
* new processes. This must be enabled on Windows (because there is no
* fork()). On other platforms, it's only useful for verifying those
* otherwise Windows-specific code paths.
*/
#if defined(WIN32) && !defined(__CYGWIN__)
#define EXEC_BACKEND
#endif
/*
* Define this if your operating system supports link()
*/
#if !defined(WIN32) && !defined(__CYGWIN__)
#define HAVE_WORKING_LINK 1
#endif
/*
* USE_POSIX_FADVISE controls whether Postgres will attempt to use the
* posix_fadvise() kernel call. Usually the automatic configure tests are
* sufficient, but some older Linux distributions had broken versions of
* posix_fadvise(). If necessary you can remove the #define here.
*/
#if HAVE_DECL_POSIX_FADVISE && defined(HAVE_POSIX_FADVISE)
#define USE_POSIX_FADVISE
#endif
/*
* USE_PREFETCH code should be compiled only if we have a way to implement
* prefetching. (This is decoupled from USE_POSIX_FADVISE because there
* might in future be support for alternative low-level prefetch APIs.
* If you change this, you probably need to adjust the error message in
* check_effective_io_concurrency.)
*/
#ifdef USE_POSIX_FADVISE
#define USE_PREFETCH
#endif
/*
* Default and maximum values for backend_flush_after, bgwriter_flush_after
* and checkpoint_flush_after; measured in blocks. Currently, these are
* enabled by default if sync_file_range() exists, ie, only on Linux. Perhaps
* we could also enable by default if we have mmap and msync(MS_ASYNC)?
*/
#ifdef HAVE_SYNC_FILE_RANGE
#define DEFAULT_BACKEND_FLUSH_AFTER 0 /* never enabled by default */
#define DEFAULT_BGWRITER_FLUSH_AFTER 64
#define DEFAULT_CHECKPOINT_FLUSH_AFTER 32
#else
#define DEFAULT_BACKEND_FLUSH_AFTER 0
#define DEFAULT_BGWRITER_FLUSH_AFTER 0
#define DEFAULT_CHECKPOINT_FLUSH_AFTER 0
#endif
/* upper limit for all three variables */
#define WRITEBACK_MAX_PENDING_FLUSHES 256
/*
* USE_SSL code should be compiled only when compiling with an SSL
* implementation. (Currently, only OpenSSL is supported, but we might add
* more implementations in the future.)
*/
#ifdef USE_OPENSSL
#define USE_SSL
#endif
/*
* This is the default directory in which AF_UNIX socket files are
* placed. Caution: changing this risks breaking your existing client
* applications, which are likely to continue to look in the old
* directory. But if you just hate the idea of sockets in /tmp,
* here's where to twiddle it. You can also override this at runtime
* with the postmaster's -k switch.
*
* If set to an empty string, then AF_UNIX sockets are not used by default: A
* server will not create an AF_UNIX socket unless the run-time configuration
* is changed, a client will connect via TCP/IP by default and will only use
* an AF_UNIX socket if one is explicitly specified.
*
* This is done by default on Windows because there is no good standard
* location for AF_UNIX sockets and many installations on Windows don't
* support them yet.
*/
#ifndef WIN32
#define DEFAULT_PGSOCKET_DIR "/var/run/postgresql"
#else
#define DEFAULT_PGSOCKET_DIR ""
#endif
/*
* This is the default event source for Windows event log.
*/
#define DEFAULT_EVENT_SOURCE "PostgreSQL"
/*
* The random() function is expected to yield values between 0 and
* MAX_RANDOM_VALUE. Currently, all known implementations yield
* 0..2^31-1, so we just hardwire this constant. We could do a
* configure test if it proves to be necessary. CAUTION: Think not to
* replace this with RAND_MAX. RAND_MAX defines the maximum value of
* the older rand() function, which is often different from --- and
* considerably inferior to --- random().
*/
#define MAX_RANDOM_VALUE PG_INT32_MAX
/*
* On PPC machines, decide whether to use the mutex hint bit in LWARX
* instructions. Setting the hint bit will slightly improve spinlock
* performance on POWER6 and later machines, but does nothing before that,
* and will result in illegal-instruction failures on some pre-POWER4
* machines. By default we use the hint bit when building for 64-bit PPC,
* which should be safe in nearly all cases. You might want to override
* this if you are building 32-bit code for a known-recent PPC machine.
*/
#ifdef HAVE_PPC_LWARX_MUTEX_HINT /* must have assembler support in any case */
#if defined(__ppc64__) || defined(__powerpc64__)
#define USE_PPC_LWARX_MUTEX_HINT
#endif
#endif
/*
* On PPC machines, decide whether to use LWSYNC instructions in place of
* ISYNC and SYNC. This provides slightly better performance, but will
* result in illegal-instruction failures on some pre-POWER4 machines.
* By default we use LWSYNC when building for 64-bit PPC, which should be
* safe in nearly all cases.
*/
#if defined(__ppc64__) || defined(__powerpc64__)
#define USE_PPC_LWSYNC
#endif
/*
* Assumed cache line size. This doesn't affect correctness, but can be used
* for low-level optimizations. Currently, this is used to pad some data
* structures in xlog.c, to ensure that highly-contended fields are on
* different cache lines. Too small a value can hurt performance due to false
* sharing, while the only downside of too large a value is a few bytes of
* wasted memory. The default is 128, which should be large enough for all
* supported platforms.
*/
#define PG_CACHE_LINE_SIZE 128
/*
*------------------------------------------------------------------------
* The following symbols are for enabling debugging code, not for
* controlling user-visible features or resource limits.
*------------------------------------------------------------------------
*/
/*
* Include Valgrind "client requests", mostly in the memory allocator, so
* Valgrind understands PostgreSQL memory contexts. This permits detecting
* memory errors that Valgrind would not detect on a vanilla build. See also
* src/tools/valgrind.supp. "make installcheck" runs 20-30x longer under
* Valgrind. Note that USE_VALGRIND slowed older versions of Valgrind by an
* additional order of magnitude; Valgrind 3.8.1 does not have this problem.
* The client requests fall in hot code paths, so USE_VALGRIND also slows
* native execution by a few percentage points.
*
* You should normally use MEMORY_CONTEXT_CHECKING with USE_VALGRIND;
* instrumentation of repalloc() is inferior without it.
*/
/* #define USE_VALGRIND */
/*
* Define this to cause pfree()'d memory to be cleared immediately, to
* facilitate catching bugs that refer to already-freed values.
* Right now, this gets defined automatically if --enable-cassert.
*/
#ifdef USE_ASSERT_CHECKING
#define CLOBBER_FREED_MEMORY
#endif
/*
* Define this to check memory allocation errors (scribbling on more
* bytes than were allocated). Right now, this gets defined
* automatically if --enable-cassert or USE_VALGRIND.
*/
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
#define MEMORY_CONTEXT_CHECKING
#endif
/*
* Define this to cause palloc()'d memory to be filled with random data, to
* facilitate catching code that depends on the contents of uninitialized
* memory. Caution: this is horrendously expensive.
*/
/* #define RANDOMIZE_ALLOCATED_MEMORY */
/*
* Define this to force all parse and plan trees to be passed through
* copyObject(), to facilitate catching errors and omissions in
* copyObject().
*/
/* #define COPY_PARSE_PLAN_TREES */
/*
* Define this to force all parse and plan trees to be passed through
* outfuncs.c/readfuncs.c, to facilitate catching errors and omissions in
* those modules.
*/
/* #define WRITE_READ_PARSE_PLAN_TREES */
/*
* Define this to force all raw parse trees for DML statements to be scanned
* by raw_expression_tree_walker(), to facilitate catching errors and
* omissions in that function.
*/
/* #define RAW_EXPRESSION_COVERAGE_TEST */
/*
* Enable debugging print statements for lock-related operations.
*/
/* #define LOCK_DEBUG */
/*
* Enable debugging print statements for WAL-related operations; see
* also the wal_debug GUC var.
*/
/* #define WAL_DEBUG */
/*
* Enable tracing of resource consumption during sort operations;
* see also the trace_sort GUC var. For 8.1 this is enabled by default.
*/
#define TRACE_SORT 1
/*
* Enable tracing of syncscan operations (see also the trace_syncscan GUC var).
*/
/* #define TRACE_SYNCSCAN */